1. Field of the Invention
The present invention relates to devices and methods for changing positions of landmarks, areas, or roads included in map information and, more specifically, to a device and method for automatically changing these positions so that the landmarks and areas do not overlap with each road displayed with a road width.
2. Description of the Background Art
Navigation devices for vehicles provide users with guidance to a destination by displaying map information stored in a storage medium, such as CD-ROM, on a screen. Such map information includes road network information, and also various facility information and area information. Facilities to be displayed on a map include post offices, convenience stores, and gas stations, for example. Areas to be displayed include seas, parks, and city blocks, for example. When the map information is displayed on a screen, the facilities are displayed as xe2x80x9clandmarksxe2x80x9d represented by graphics, characters, or a combination of both. The areas are defined by polygons. Hereinafter, the landmarks and the areas included in the map information are collectively referred to as xe2x80x9cobjectsxe2x80x9d. Vehicle navigation devices are intended to provide users with guidance to a destination by appropriately displaying road network information and object information both included in map information.
Conventional vehicle navigation devices display map information as a plain view or a perspective view from the top. Most of these devices display roads each as a line segment having a negligible width, without reflecting their actual road widths. Such display is hereinafter referred to as xe2x80x9czero-width displayxe2x80x9d. For vehicle navigation devices carrying out zero-width display, map information is generated to support zero-width display. Therefore, as shown in FIG. 27a, roads and objects can be simultaneously displayed while almost keeping the actual positional relation therebetween. Thus, there do not exist significant problems on a display screen.
On the other hand, for better destination guidance to users, some vehicle navigation devices may display each road with its own road width. Such display is hereinafter referred to as xe2x80x9cwidth displayxe2x80x9d. Such width display is adopted especially by vehicle navigation devices carrying out three-dimensional display of roads each provided with height. The reason is that displaying roads each provided only with height causes a difficulty for users in recognizing the shape of the roads. To reduce such difficulty, width display is very effective. For width display, however, enormous amount of data is required as the map information. Therefore, the existing map information for zero-width display is preferably used for width display without generating another map information.
However, if the map information for zero-width display is used for width display, the roads and objects may overlap each other, as shown in FIG. 27b. In FIG. 27b, a landmark that represents a post office and an area are displayed on a screen, overlapping with a road with a road width. Such display screen is quite awkward for users, who expect reality in road display.
One solution to the above problem is to generate another map information dedicated to width display. However, such map information is enormous in volume, as stated above, and therefore the existing map information for zero-width display is preferably used for generating new map information. Also, for devices capable of switching between width display and zero-width display by user""s selection or capable of switching the road width to another one for display, it is preferable that only single map information is commonly used for every case without having plural map information.
Therefore, an object of the present invention is to provide a device and method for automatically changing a position of an object or a road on a map so that the object does not overlap with the road displayed with a road width.
The present invention has the following features to achieve the object mentioned above.
A first aspect of the present invention is directed to a map information changing device for changing positions of landmarks and areas included in map information, the device including: a map information storage for storing the map information at least related to roads, the landmarks, and the areas; an overlap determination unit for determining whether the landmark and the area included in the map information overlap with the road included in the map information and displayed with a road width; a position changer for changing positional information of the landmark and the area determined by the overlap determination unit as overlapping with one or more roads by moving each of the landmark and the area to a position at which each of the landmark and the area does not overlap with the one or more roads displayed with the road width, while keeping each location side of the landmark and the area with respect to a center line of each road; and a changed map information storage for storing the map information and the positional information of the landmark and the area changed by the position changer.
In such map information changing device, the landmark and the area are changed in position so as not to overlap with the roads displayed with the road width, while keeping each location side of the landmark and the area with respect to the center line of each road. Therefore, when the map information is displayed on a screen with the road width based on the original map information and the changed positional information, the landmark and the area are displayed so as not to overlap with the road. Thus, a realistic screen can be presented to the user.
In this case, the position changer may move the landmark or each vertex of the area away from the center line of each of the one or more roads. To move each vertex of the area, the position changer may deform the area in a direction away from the center line of each of the one or more roads, or may translate the area away from the center line of each of the one or more roads. According to the area deforming method, the area is deformed to be reduced in size. Such reduced area will not cause another overlap with a road, and therefore only one process is enough for each road. Consequently, it is possible to change the positional information with a small amount of calculation. On the other hand, according to the areas moving method, the area is moved as keeping its shape. Therefore, it is possible to prevent the user from erroneously recognizing the shape of the area.
According to a second aspect of the present invention, in the first aspect, the map information changing device further includes a map information display unit for displaying, on a screen, the changed map information stored in the changed map information storage with the road width. In such a map information changing device, the roads, landmarks and areas are displayed on a screen based on the original map information and the changed positional information. The landmark and the area are displayed so as not to overlap with the road. Thus, a realistic screen can be presented to the user.
In this case, the overlap determination unit and the position change unit may switch the road width to another road width based on an input from a user. Thus, even if the road width is switched based on the selection by the user, the landmark and the area are always displayed so as not to overlap with the roads. Therefore, a realistic screen can be presented to the user without requiring a plurality of map information provided in advance.
Furthermore, if the map information changing device equipped with the map information display unit is incorporated in a navigation device, the landmark and the area are displayed so as not to overlap with the roads displayed with the road width. Therefore, a realistic screen can be presented to the user.
A third aspect of the present invention is directed to a method for changing positions of landmarks and areas included in map information, the method including the steps of: storing the map information at least related to roads, the landmarks, and the areas; determining whether the landmark and the area included in the map information overlap with the road included in the map information and displayed with a road width; changing positional information of the landmark and the area determined in the overlap determining step as overlapping with one or more roads by moving each of the landmark and the area to a position at which each of the landmark and the area does not overlap with the one or more roads displayed with the road width, while keeping a location side of each of the landmark and the area with respect to a center line of each road; and storing the map information and the positional information of the landmark and the area changed in the positional information changing step.
In such a map information changing method, the landmark and the area are changed in position so as not to overlap with the roads displayed with the road width, while keeping each location side of the landmark and the area with respect to the center line of each road. Therefore, when the map information is displayed on a screen with the road width based on the original map information and the changed positional information, the landmark and the area are displayed so as not to overlap with the road. Thus, a realistic screen can be presented to the user.
In this case, in the positional information changing step, the landmark or each vertex of the area may be moved away from the center line of each of the one or more roads. To move each vertex of the area, in the positional information changing step, the area may be deformed in a direction away from the center line of each of the one or more roads, or translated away from the center line of each of the one or more roads. According to the area deforming method, the area is deformed to be reduced in size. Such reduced area will not cause another overlap with roads, and therefore only one process is enough for each road. Consequently, it is possible to change the positional information with a small amount of calculation. On the other hand, according to the area moving method, the area is moved as keeping its shape. Therefore, it is possible to prevent the user from erroneously recognizing the shape of the area.
A fourth aspect of the present invention is directed to a map information changing device for changing positions of roads included in map information, the device including: a map information storage for storing the map information at least related to the roads, landmarks, and areas; an overlap determination unit for determining whether the road included in the map information and displayed with a road width overlaps with the landmark and the area included in the map information; a position changer for changing positional information of the road determined by the overlap determination unit as overlapping with one or more landmarks and areas by moving the road displayed with the road width to a position at which the road does not overlap with the one or more landmarks and areas, while keeping a location side of each of the landmarks and the areas with respect to a center line of the road; and a changed map information storage for storing the map information and the positional information of the road changed by the position changer.
In such a map information changing device, the road displayed with the road width is changed in position so as not to overlap with the landmark and the area. Therefore, when the map information is displayed on a screen with the road width based on the original map information and the changed positional information, the road is displayed so as not to overlap with the landmark and the area. Thus, a realistic screen can be presented to the user.
In this case, the position changer may move each endpoint of a segment composing the road away from the one or more landmarks and areas. Alternatively, the position changer may translate the road away from the one or more landmarks and areas. Also, the position changer may move one endpoint of the segment composing the road away from the one or more landmarks and areas. In either case, the road displayed with the road width is changed in position so as not to overlap with the landmark and the area. Therefore, when the map information is displayed on a screen with the road width based on the original map information and the changed positional information, the road is displayed so as not to overlap with the landmark and the area.
According to a fifth aspect of the present invention, in the fourth aspect, the map information changing device further includes a map information display unit for displaying, on a screen, the changed map information stored in the changed map information storage with the road width. In such map information changing device, the road, landmark, and area are displayed on a screen, based on the original map information and the changed positional information. The road is displayed so as not to overlap with the landmark and the area. Thus, a realistic screen can be presented to the user.
In this case, the overlap determination unit and the position changer may switch the road width to another road width based on an input from a user. Consequently, even if the road width is switched based on the selection by the user, the road is always displayed so as not to overlap with the landmark and the area. Therefore, a realistic screen can be presented to the user without requiring a plurality of map information provided in advance.
Furthermore, if the map information changing device equipped with the map information display unit is incorporated in a navigation device, the roads displayed with the road width are displayed so as not to overlap with the landmark and the area. Therefore, a realistic screen can be presented to the user.
A sixth aspect of the present invention is directed to a method for changing positions of roads included in map information, the method including the steps of: storing the map information at least related to the roads, landmarks, and areas; determining whether the road included in the map information and displayed with a road width overlaps with the landmark and the area included in the map information; changing positional information of the road determined in the overlap determining step as overlapping with one or more landmarks and areas by moving the road displayed with the road width to a position at which the road does not overlap with the one or more landmarks and areas, while keeping a location side of each of the landmarks and the areas with respect to a center line of the road; and storing the map information and the positional information of the road changed in the positional information changing step.
In such a map information changing method, the road displayed with the road width is changed in position so as not to overlap with the landmark and the area. Therefore, when the map information is displayed on a screen with the road width based on the original map information and the changed positional information, the road is displayed so as not to overlap with the landmark and the area. Thus, a realistic screen can be presented to the user.
In this case, in the positional information changing step, each endpoint of a segment composing the road may be moved away from the one or more landmarks and areas. Alternatively, the road may be translated away from the one or more landmarks and areas. Also, one endpoint of the segment composing the road may be moved away from the one or more landmarks and areas. In either case, the road displayed with the road width is changed in position so as not to overlap with the landmark and the area. Therefore, when the map information is displayed, based on the original map information and the changed positional information, on a screen with the road width provided thereto, the road is displayed so as not to overlap with the landmark and the area.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.